1. Field of the Invention
This invention relates to an improved hand-operated or manual pump for fluid. This invention also relates to an improved Ambu bag which can be operated by a single person for a long time.
2. Prior Art
A popular conventional hand-operated pump comprises a cylindrical bellows body formed of a flexible plastic or rubber material, which may be made thick and resilient so as to assist to restore its expanded or original configuration after the bellows body is manually pressed from both sides with two hands and contracted along its axis to discharge fluid. When the resilience of the bellows body is insufficient, the manual pump requires considerable manual assistance to return to its expanded state to charge fluid. When the resilience of the bellows body is excessive, the manual pump requires its operator to exert considerable energy to contract the bellows body.
Another conventional manual pump utilizes repulsion means such as a coil spring installed within its cylindrical bellows body so that the coil spring may assist the bellows body to restore its expanded configuration after the bellows body is contracted. Such a spring-assisted manual pump is disclosed in Japanese Utility Model Application Laid-Open Publication No. 48-96503, which requires use of both hands of an operator.
Japanese Utility Model Application Laid-Open Publication No. 55-60481 discloses a vacuum packer including a spring-assisted manual pump comprising a curved base having air charge and discharge means and a plastic bellows pump cylinder body. This device also requires use of both hands.
All those manual pumps not only require use of both hands of an operator but also keep occupying both hands, preventing the operator from doing anything else while operating the manual pumps.
When such a pump mechanism is incorporated into an Ambu bag, properly holding a facemask of the Ambu bag on a patient while concurrently activating the Ambu bag is virtually impossible for a single operator since both hands of the operator are kept on the bag. Such an Ambu bag requires at least two persons for a practical medical operation.
Another conventional Ambu bag is shown in FIG. 5, indicated by "70", comprising a rugby ball-like bag or chamber 80 and a facemask device 40 connected to the chamber 80 in fluid communication. The bag 70 is generally made of a "thick" and resilient rubber material to provide quick recovery of shape of the bag after its deformation with a hand or hands. Although it may be possible to activate the pump chamber 80 with a single hand, it is very energy consuming or fatiguing to keep activating or repeatedly squeeze such a thick bag for a long time with a single hand as will be readily understood by medical practitioners. The operator will frequently have to switch hands or use both hands, or another person must take over the operation. Thus, it usually requires at least two medical persons to apply an Ambu bag on a patent for a long time, one squeezing the bag and the other applying a facemask.